ANCHORAGE — An icebreaker carrying a key piece of equipment for Arctic drilling planned by Royal Dutch Shell off the northern coast of Alaska was forced to return to dock after a hole more than three feet long was discovered in its hull, the company said Tuesday.

It was unclear if the mishap would delay Shell’s plan for drilling this summer.

The crew of the Fennica discovered the leak in a ballast tank on Friday as the ship was leaving the channel in Dutch Harbor, Alaska, on its way to the Arctic, Shell spokesman Curtis Smith said.

ANCHORAGE — Polar bears are at risk of dying off if humans don’t reverse the trend of global warming, a blunt U.S. government report filed Thursday said.

“The single most important step for polar bear conservation is decisive action to address Arctic warming,” the U.S. Fish and Wildlife Service said in a draft recovery plan, part of the process after the agency listed the species as threatened in 2008.

“Short of action that effectively addresses the primary cause of diminishing sea ice, it is unlikely that polar bears will be recovered.”

ANCHORAGE — About a third of the world’s polar bears could be in imminent danger from greenhouse gas emissions in as soon as a decade, a U.S. government report shows.

The U.S. Geological Survey, the Interior Department’s research arm, said updated scientific models don’t bode well for polar bear populations across the world, especially in Alaska, the only state in the nation with the white bears.

ANCHORAGE — Eight cruise ship passengers and their pilot died on a sightseeing excursion in Alaska when their small plane crashed in remote and rugged terrain.

Wind and rain prevented any recovery after the wreckage of the aircraft was found Thursday against a granite rock face, 800 feet above a lake, in southeastern Alaska. Emergency crews on Friday will try to recover the remains of the victims, whose names have not been released.

COLONY GLACIER — Scientists and volunteers tethered in safety gear and ice cleats painstakingly scoured the frozen dirt and ice to see if a glacier had given up any more of its dead before they are swept into a lake and lost to history.

Fifty-two service members died when their airplane smashed into an Alaska mountain more than 60 years ago. The wreckage was rediscovered in 2012, and the somber recovery effort resumed this month.

HOUSTON — Fire crews are battling two serious wildfires in Alaska that are threatening hundreds of residences and have forced numerous evacuations.

The most recent fire erupted Monday and burned six structures and prompted hundreds of residents to flee homes on the Kenai Peninsula, roughly 150 miles south of major wildfire that started a day earlier near Willow in the heart of the state's sled-dog community.

ANCHORAGE — A powerful earthquake sent some coastal Alaska residents running for higher ground in fear they would be swamped by a tsunami, a disaster that never materialized after the shaking that did little more than knock pictures off walls.

The magnitude-6.7 quake struck at 11 p.m. Thursday and was centered in the ocean about 35 miles beneath the seabed and some 400 miles southwest of Anchorage, the U.S. Geological Survey said. It hit a remote and lightly populated Aleutian Island region.